In general, an optical device, namely, a light emitting diode (LED) is called an inter-metallic compound joining diode which produces minority carriers (electrons or electron holes) injected using a p-n junction structure of a semiconductor, and emits light by changing electrical energy into light energy due to a recombination of these carriers. That is, when a forward voltage is applied to a semiconductor of a specific element, electrons and electron holes are rejoined each other while the electrons and electron holes move through a junction part of a positive pole and a negative pole. At this time, since energy smaller than when the electrons and the electron holes are apart is generated, the light is emitted due to a difference of the generated energy. This LED is applied to a lighting device or a backlight device of an LCD device as well as a general display device, and its application range has been gradually diversified.
FIG. 1 illustrates a cross-section view of an optical device package according to a conventional art.
Referring to FIG. 1, the optical device package according to a conventional art includes an insulating layer 30 on which via holes are formed, an adhesive layer 31 formed on one surface of the insulating layer 30, a metal layer 34 attached onto the adhesive layer 31, and an optical device 37 mounted on a part of the metal layer 34 exposed to the outside through the via holes.
The optical device package of FIG. 1 is manufactured according to a process illustrated in FIG. 2.
FIG. 2 is a view showing a manufacturing process of the optical device package according to the conventional art.
Referring to FIG. 2, the adhesive layer 31 is first applied to one surface of the insulating layer 30 (S1). Here, the insulating layer 30 is generally implemented using a polyimide film. After the adhesive layer 31 is applied to the insulating layer 30, via holes 33 are formed on the insulating layer 30 (S2).
Next, the metal layer 34 is laminated on the adhesive layer 31. The metal layer 34 is preferably composed of Cu. Since then, after a surface of the metal layer is activated through several chemical treatments, photoresist is applied thereto, and an exposure process and a developing process are carried out. After the developing process is completed, a necessary circuit is formed through an etching process, and a circuit pattern layer 35 is formed by making the photoresist thin (S4). In other words, the circuit pattern layer 35 is formed by etching the part of the metal layer 34 along a predetermined pattern. Thus, the adhesive layer 31 is exposed by an etched part 40 of the circuit pattern layer 35.
By the way, since the adhesive layer 31 is generally formed of an adhesive of a transparent material, the insulating layer 30 passing through the adhesive layer is exposed to the etched part 40 of the circuit pattern layer 35. Since the polyimide which forms the insulating layer 30 has brown, the etched part 40 of the circuit pattern layer 35 appears brown.
Light emitted from the optical device 37 is reflected by a lens 9 (not shown) which covers an upper part of the optical device package 37 to thereby hit against the metal pattern layer 35 on which the optical device is mounted. The light hit against the circuit pattern layer 35 is reflected by the circuit pattern layer 35. The light hit against the etched part of the circuit pattern layer 35 is not reflected by the brown insulating layer 30, but is trapped. As a result, it is problematic that luminous intensity of the optical device package is deteriorated.
To prevent the light emitted from the optical device 37 from being trapped, a printing process has been added to thereby print a white solder resist on the etched part of the circuit pattern layer 35 or a method of reducing a pattern space of an isolated part has been used. However, this generates the problems such as an increase in process costs and restrictions on a pattern design.